micropip.freeze fails when a pypi package would clobber a bundled pyodide package

[bollwyvl]

With micropip 0.8, overloading a package as shipped in the pyodide distribution's pyodide-lock.json with an explicit wheel from e.g. PyPI fails:

# on https://pyodide.org/en/0.27.0/console.html
import micropip
>>> await micropip.install(["https://files.pythonhosted.org/packages/2d/14/d1bf3b7141ad5a42c26e4173a69e3e6529bd92b05bc587c570d28b6a3ce8/pyodide_http-0.2.1-py3-none-any.whl"])
>>> micropip.freeze()
Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/lib/python3.12/site-packages/micropip/package_manager.py", line 175, in freeze
    return freeze_lockfile(self.repodata_packages, self.repodata_info)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/lib/python3.12/site-packages/micropip/freeze.py", line 16, in freeze_lockfile
    return json.dumps(freeze_data(lockfile_packages, lockfile_info))
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/lib/python3.12/site-packages/micropip/freeze.py", line 27, in freeze_data
    packages = dict(sorted(package_items))
                    ^^^^^^^^^^^^^^^^^^^^^
TypeError: '<' not supported between instances of 'dict' and 'dict'

This is likely because:

sorted([("pyodide-http", {}), ("pyodide-http": {})])

... leads to a comparison of the second member of the tuples as a tiebreaker.

[bollwyvl]

Here is a strawman PR which removes the itertools import, and just accepts that merging and sorting two dict instances is hard with iterators.

#172